Carboxyl group is one of important functional groups in pharmaceutical compounds, and is widely used in combination with various functional groups, such as amino group, hydroxyl group, and a halogen atom. For example, gabapentin (2-[1-(aminomethyl)cyclohexyl]acetic acid) used an antiepileptic, and pregabalin ((S)-3-(aminomethyl)-5-methylhexanoic acid) used for peripheral neuropathic pains (postherpetic neuralgia and the like) are examples of medicaments having carboxyl group and amino group in combination.
There have been proposed pharmaceutical compounds consisting of a carboxylic acid derivative in which a carbon atom is replaced with a silicon atom. For example, a β-carbonylsilane compound having a silicon atom as a ring-constituting atom in a ring system such as 6-membered ring has been proposed as an analogue of gabapentin (GB 2,397,576A), and it is taught that this compound can be used as a pharmaceutical compound (Journal of Organometallic Chemistry, 690, pp. 678-684, 2005, with reference to the method for preparation of this compound). However, any compounds corresponding to pregabalin of which carbon atom in the fundamental structure thereof is replaced with a silicon atom are not known.